Information useful in estimating the occupational fluoride hazard to pregnant women is scanty. Fluoride excretion and balances were determined in 18 young women–seven who were not pregnant, six in early pregnancy (second quarter), and five in late pregnancy (fourth quarter)–over a 20-day period under confined metabolic conditions. The total fluoride intake averaged 1.35 mg/day (0.35 mg from the diet, 1 mg from a mineral capsule). Urinary fluoride excretion levels for the three groups were similar and averaged 0.95, 1.03, and 1.15 mg/day, respectively. On the average, 88% of the total fluoride excreted was in the urine and the remainder in the feces. With few exceptions, the women in each group demonstrated small positive balances; the averages were +0.19, +0.16, and +0.14 mg/day, respectively. The differences were small and not statistically significant (p greater than 0.1). These data indicate that fluoride metabolism is not markedly altered during the course of pregnancy.